1. Field of the Invention
The present invention relates to headlamp assemblies for motor vehicles, equipped with one or more radiating members capable of radiating heat energy generated by one or more light sources.
2. Description of the Related Art
There are various types of headlamp assemblies mounted to motor vehicles equipped with light emitting diodes. For example, Japanese patent No. JP4289268 has disclosed such a headlamp assembly comprised of a headlamp and a light emitting diode. In the headlamp assembly, a light projection lens, a shade and a light source are arranged in turn, and a reflector is arranged so that it faces the light source. The reflector reflects the light generated by the light source to the forward direction. One or more radiating members are mounted to the light source in order to radiate the heat energy generated in the light source.
In the headlamp assembly, the light source is comprised of a first light source and a second light source. The first light source has a first light emission part which is vertically placed at an upper part observed from an optical axis of the light source. The second light source has a second light emission part which is vertically placed at a lower part observed from the optical axis of the light source. That is, the headlamp assembly generates two types of light beam patterns.
In general, a light emitting diode has an intrinsic drawback because of having a high heat density. For example, when the temperature of a light emitting diode increases, the light emitting efficiency is decreased, and its lifetime becomes short. Therefore, when light emitting diodes are closely arranged to each other and a small sized radiating member is used for decreasing the entire size of the headlamp assembly, the heat generation density becomes high and the heat radiating capability of the headlamp assembly is decreased.
In order to avoid the above conventional drawback, there are conventional techniques. For example, Japanese patent laid open publication No. JP 2005-190825 has disclosed such a conventional technique in which a headlamp assembly is equipped with an electric fan. The electric fan makes air flow from the rear side of a lamp chamber to the front side of the lamp chamber. Thus, the electric fan forcedly makes the heated air flow from the rear side of the lamp chamber toward the front side of the light chamber in order to cool the inside of the light chamber.
Further, Japanese patent laid open publication No. JP 2009-147175 has disclosed another conventional technique in which a coolant flows through a cooling pipe in a printed circuit board on which one or more light emitting diodes are arranged in order to cool the light emitting diodes, and the coolant is supplied by a pump to the radiating plate through the cooling pipe in order to radiate heat energy from the radiating plate. This conventional technique increases the heat radiating capability.
However, the conventional techniques previously described require an electric fan in a lamp chamber and/or a pump and a cooling pipe in order to forcedly cool the light emitting diodes. This increases the entire size of the headlamp assembly, and electric power consumption because the conventional headlamp assemblies further need to have additional electric power in order to drive the above electric fan and pump.